The most dynamic segment of orthopedic and neurosurgical medical practice over the past decade has been spinal devices designed to fuse the spine to treat a broad range of degenerative spinal disorders. Back pain is a significant clinical problem and the annual costs to treat it, both surgical and medical, is estimated to be over $2 billion. Motion preserving devices to treat back and extremity pain have, however, created a treatment alternative to or in combination with fusion for degenerative disk disease.